8d Notice of a Geological Model. 



those levels along the crests of the ridges, when not broken by 

 transverse fissures. The Blue or Kittatinny Mountain, the south- 

 ernmost of these nearly parallel ranges, is probably the highest. 

 The coal range is next in elevation, and there is some lofty 

 ground, forming Short Mountain, between Peter's and Berry's 

 mountains. 



Geological Features. — Under this head we shall here be very 

 brief; because that subject is not the primary object of this ad- 

 dress ; and because the region has received or will receive, ample 

 investigation by the state geological survey, with all the combined 

 advantages resulting from the official resources, the science and 

 the experience of its able conductor. The results of that great 

 work it would be premature to anticipate. The positions of the 

 various formations and of the respective members of the groups 

 of strata, within these limits, have already been indicated in the 

 annual reports of Professor Rogers. 



In contemplating this region, it appears to us that its most inter- 

 esting features are attributable to the undulating and broken or 

 upheaved character of the formations, by which process some of 

 them are repeatedly brought to the surface, in long elevated 

 ridges, and again dip at high angles and form basins which en- 

 close or support the superior strata — the carboniferous series being 

 of course the highest. These circumstances confer a remarkably 

 picturesque character upon the scenery, particularly where these 

 parallel ridges are intersected by the Susquehanna, the Juniata, 

 and the Swatara rivers. No part of Pennsylvania is so rich in 

 pictorial beauty as the borders of the noble Susquehanna, or has 

 furnished so many subjects for the skill of the painter. 



The spectacle here presented, by this river, cutting across in 

 its singular passage, nearly at right angles, through so many ridg- 

 es of extremely hard rocks, would of itself furnish a theme for 

 geological speculation. Phenomena like these are well illustrated 

 by the mode of representation we have adopted. The numerous 

 cross fractures marked by the frequent gaps through the moun- 

 tains and by the remarkable ramifications of the Swatara, in the 

 Pinegrove coal region, could by no other process of exhibition 

 be rendered so intelligible. 



The Coal Formation. — It forms no part of the plan of the wri- 

 ter to encumber this communication with minute details. With 

 regard to the southern branch, more especially, it is the less neces- 



